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/*
* BK Id: SCCS/s.semaphore.h 1.15 05/17/01 18:14:25 cort
*/
#ifndef _PPC_SEMAPHORE_H
#define _PPC_SEMAPHORE_H
/*
* Swiped from asm-sparc/semaphore.h and modified
* -- Cort (cort@cs.nmt.edu)
*
* Stole some rw spinlock-based semaphore stuff from asm-alpha/semaphore.h
* -- Ani Joshi (ajoshi@unixbox.com)
*
* Remove spinlock-based RW semaphores; RW semaphore definitions are
* now in rwsem.h and we use the the generic lib/rwsem.c implementation.
* Rework semaphores to use atomic_dec_if_positive.
* -- Paul Mackerras (paulus@samba.org)
*/
#ifdef __KERNEL__
#include <asm/atomic.h>
#include <asm/system.h>
#include <linux/wait.h>
#include <linux/rwsem.h>
struct semaphore {
/*
* Note that any negative value of count is equivalent to 0,
* but additionally indicates that some process(es) might be
* sleeping on `wait'.
*/
atomic_t count;
wait_queue_head_t wait;
#if WAITQUEUE_DEBUG
long __magic;
#endif
};
#if WAITQUEUE_DEBUG
# define __SEM_DEBUG_INIT(name) \
, (long)&(name).__magic
#else
# define __SEM_DEBUG_INIT(name)
#endif
#define __SEMAPHORE_INITIALIZER(name, count) \
{ ATOMIC_INIT(count), \
__WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \
__SEM_DEBUG_INIT(name) }
#define __MUTEX_INITIALIZER(name) \
__SEMAPHORE_INITIALIZER(name, 1)
#define __DECLARE_SEMAPHORE_GENERIC(name, count) \
struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name, 1)
#define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name, 0)
static inline void sema_init (struct semaphore *sem, int val)
{
atomic_set(&sem->count, val);
init_waitqueue_head(&sem->wait);
#if WAITQUEUE_DEBUG
sem->__magic = (long)&sem->__magic;
#endif
}
static inline void init_MUTEX (struct semaphore *sem)
{
sema_init(sem, 1);
}
static inline void init_MUTEX_LOCKED (struct semaphore *sem)
{
sema_init(sem, 0);
}
extern void __down(struct semaphore * sem);
extern int __down_interruptible(struct semaphore * sem);
extern void __up(struct semaphore * sem);
extern inline void down(struct semaphore * sem)
{
#if WAITQUEUE_DEBUG
CHECK_MAGIC(sem->__magic);
#endif
/*
* Try to get the semaphore, take the slow path if we fail.
*/
if (atomic_dec_return(&sem->count) < 0)
__down(sem);
smp_wmb();
}
extern inline int down_interruptible(struct semaphore * sem)
{
int ret = 0;
#if WAITQUEUE_DEBUG
CHECK_MAGIC(sem->__magic);
#endif
if (atomic_dec_return(&sem->count) < 0)
ret = __down_interruptible(sem);
smp_wmb();
return ret;
}
extern inline int down_trylock(struct semaphore * sem)
{
int ret;
#if WAITQUEUE_DEBUG
CHECK_MAGIC(sem->__magic);
#endif
ret = atomic_dec_if_positive(&sem->count) < 0;
smp_wmb();
return ret;
}
extern inline void up(struct semaphore * sem)
{
#if WAITQUEUE_DEBUG
CHECK_MAGIC(sem->__magic);
#endif
smp_wmb();
if (atomic_inc_return(&sem->count) <= 0)
__up(sem);
}
#endif /* __KERNEL__ */
#endif /* !(_PPC_SEMAPHORE_H) */
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